Thermostatic switch



Oct. 20, 1953 A. D. SLATKIN THERMOSTATIC SWITCH Filed Jan. l5, 1949 INVENTOR. ALFRED D. SLATKIN ATTORN S Patented Oct. 20, 1953 "THERMOSTATIC 'SWITCH Alfred '.Slatkin, Birmingham, Mich., assi'gnor to Moth-King Corporation, Detroit, .Mich., a

yconporation.of Michigan Application January 15, $1949, "SeriaPNm V71105 (Cl. '20D-138) 41V`Claims. vl My invention relates to electric heaters vandto a switch construction therefor. `More particularlr, 'the present 'invention yis applicable to a Vaporizer for heating and vaporizing an insec- 4ticide or other similar matter, and `embodies ya switch vdevice employing a thermal responsive `element mounted 1in fthe air fjacket in said Eheater and operable vto vautomatically lopen the switch 4at the proper time.

Whereas, insecticide lvaporizers require heat to function properly, 'they areusually dangerous to use because'o'f Athe lackfof control. In the present construction, the control is 'had by means or the particular switch construction that has Abecome an actual part of `the production prodland which meets the rigid requirements of the industry and those `Who lmust approve of such electrical apparatus, has'become of late exceedngly diiiicult to produce.

It is an object of the present invention tofover- `come the aforesaid production dilliculties by constructing an electric'heater equipped -with a simplified switch construction that A:is tautomati- -cally operable to control the operation lof the heater, 'but is quitecompetitivecommercially and simple and economical to manufacture.

Another object of the present invention is lto provide a simplified automatic switch for 'elec- :tric heaters or the like by constructing a switch utilizing a bimetal thermal vresponsive element Vadapted Ito *latch vthe switch arm to maintain electrical ycontact and yoperable vto release the 'latch at lthe rproper Stime.

These yand other objects `will'ibe more readily apparent as the description progresses in which reference is had to the accompanying drawing illustrating a `preferred embodiment of the vinvention and in which `like parts are vreferred to by like characters throughout lthe/several views, and inwhich Fig. :l is a side yeleva'tionalview of an electric :heater partlyin-seotion pon the line I--zl :of,Fig.;2. Fig. 2 is a plan :view ,of ,the base .on'which ,is

mounted the electric switch and taken A on the line 2 2 of Fig. 1.

Figs. 3, 4 and 5 yare detail sectional `views ofthe switch respectively ,showing three vpositions thereof, and

Figs. .6 and f7 lare fragmentary detail sectional ceptacle.

2 views showing the action of the switch latchling means.

The electric vheater as illustrated in the accompanying drawing is utilized principally ior vaporizing an insecticide or other similar material, although the principles of the invention may be readilyembodied in other types of electrical devices. The present heater comprises an outer shell or'housing I0 land a reentrant recess or receptacle H, so "spaced from the `outer shell 4as to provide anair 'jacket surrounding said rc- A-closure plate l2 Vis secured to close the'bottom open end of lsaid shell, the same being secured in place by a spring ring I 3 or other ksuitable securing means. The housing l0 is provided -with vleg extensions i4, and a cover I5 is 'provided iorclosing the upper open end of the recess orreceptacle. The closure plate may be vconsidered asfa base plate and the same is preferably constructed of insulating material such as hardrubbery ya phenol resin or the like.

The 'switch -'and :heating element is supported yby the base plate 112, said heating element 'Ztl being o'f any vconventional construction but preferably'being vof such shape and construction as to directly heat the receptacle or Apot and to be 4mounted on suitable brackets 2l fixed or otherwise secured tothe baseplate I2. A switch desrignated as a Whole Iby the reference character 25 lisalso `mounted or carried by this base or closure 'plate |2, said 'switch ybeing preferably mounted Onapost 26 as will 'be lhereinafterdescribed .in

detail.

A lead-in electric oord 2l lis threaded through The post 25 is being lalso provided `forreceiving the bolt or rivet -32 which is provided yto secure the switch arms tosaidpost. A spring'arm structure 33 is assembled -in theslot 28, said'arrn structure comprising Ia ypair ofr'afrms 33a and 33h, said portion consisting-oi a vstraight length of spring steel ribbon stock 4and 33h consisting rci" a similar length of spring steel, but upwardly bent as at and carrying a contact-point or button 35.

A loi-metal thermal responsive element at is lassenibled above vthe spring arm structure Aand mounted yon the post `26 similarly to the spring arm 33 and carries a contactpoint 'or button 3l which lisaligncd withthe contact point or button 35. The spring arm and element 4are spaced v,apart sa suitable insulating Y.Washer S8 ,and one lead .525m .of the electric :cord isattached orfotherwise electrically connected to the arm 33 while the other lead is connected to the heating element. A connector connects the bi-metal element to the other end of said heating element.

Both said spring arms 33a and 33h, as well as the bi-metal element 3G, are provided with enlarged portions le which are piloted or otherwise closely fitted into the bored recess Sil of the post, both said spring arms and element being also provided with holes lil and 42 respectively of a diameter greater than the diameter of the bolt or rivet 32, said holes el and 42 being concentric with the enlarged portions 40 and thus as the spring arm and element are assembled to the post, the edges of the holes ci are concentrically spaced from the bolt A Washer 5.2 is mounted on top of the bi-metal element 36 and the bolt or rivet secures the whole assembly together.

The 'oi-instal element 3S comprises a return bent extension which is constructed to be engage1 by the tip of the spring steel arm 33a to latch the spring arm to said element and maintain the c^ntact points or buttons 35 and 37 in Contact with each other.

The current to the heating element is turned on by actuation of the button and this action is illust-'ated in Figures 3 to 5 inclusive. The button is supported in any conventional way by the base plate l2 and the same is pushed against the spring arm structure, moving the same towards the element 3S. The contacts and 35 engage nrst (see Fig. e), but arm 33a is still not engaged with the element extension d5. Further movement of the actuator button #it further springs the arm which carries the contact point S5 increasing the pressure of the contact and said spring arm 33a is sprung past the tip of extension f2.5 and is latched therewith seen in Fig. 5.

The contacts 35 and El thus remain closed and the button Il@ is free to drop away. As the electric 'neatinCr device heats up, the interior of the device becomes and the air therein gets hotter and hott-er. In time, the heat is carried to the bimetal element 355 causing the same to bend upwardly due to the unequal expansion of the bimetal thermostatic sections, and causing the return bent extension to open up until eventually 'l e spring arm member 33a is free to slip past the tip of this return bent extension 45. The

spring arm then snaps back to its original posi- 4 tion (see Fig. 7), the current to the heating element is automatically turned off since the contact between 35 and 3l is broken, as is likewise the contact between the spring arm member 33a and extension e5. The whole device is permitted to cool and the bimetal element slowly returns to the position shown in Fig. 3, where it is in readiness to again be actuated when desired.

It is thus seen that the present switch device is of simple construction and of economical manufacture. The heating device is readily and economically serviced since the base and its various mechanisms can be removed as a unit, by disconnecting a few connections, and replaced with a ner.7 unitary sub-assembly.

It will be apparent to those skilled in the art to which this invention pertains that various changes and minor modiiications may be made to the embodiment illustrated and described without departing from the spirit of the invention or from the scope of the appended claims.

I claim:

l. A thermal responsive switch means for an. electric heating device comprising a spring arm structure having an intermediate contact button, a bimetal thermal responsive element having an intermediate contact button relatively aligned with the contact button on said spring arm structure, means supporting said arm structure and element, an actuator supported for engagement with said spring arm structure and arranged to be manually actuated to move said spring arm structure in order to engage said contact buttons, and means latching said arm structure to the free end of said element to maintain contact between said buttons, said latching means operable in response to a predetermined increase in temperature to disengage the element from said spring arm whereby to release said latching means and to thereby permit the spring arm structure to return to its original position and to open the contact between said buttons.

2. A thermal responsive switch means for an electric heating device comprising a spring arm structure having a resiliently supported intermediate contact button, a bi-metal thermal responsive element having an intermediate contact button relatively aligned with the contact button on said spring arm structure, means supporting said arrn structure and element, an actuator supported for engagement with said spring arm structure and arranged to be manually actuated to move said spring arm structure in order to rst engage said contact buttons, and means operable by further movement of said spring arm structure for latching said arm structure to the free end of said element to maintain contact between said buttons, said latching means operable in response to a predetermined increase in temperature to disengage the element from said spring arm to release said latching means and to thereby permit the spring arm structure to return to its original position and to open the contact between said buttons, said latching means comprising return bent extension of said bimetal element and formed to yieldingly engage said under spring arm structure.

3. A thermal responsive switch means for an electric heating device comprising a spring arm structure having a resiliently supported intermediate contact button, a bimetal thermal responsive element having an intermediate contact button relatively aligned with the contact button on said spring arm structure, means supporting said arm structure and element, an actuator supported for engagement with said spring arm structure and arranged to be manually actuated to move said spring arm structure in order to rst engage said contact buttons, and means operable by further movement of said spring arm for latching said arm structure to the free end of said element to maintain contact between said buttons, said latching means operable in respense to a predetermined increase in temperature to disengage the element and spring arm to release said latching means and to thereby permit the spring arm structure to return to its original position and to open the contact between said buttons, said latching means comprising a return extension of said bimetal element disposed so that said spring arm structure can be forced past the end of said extension on making contact with said element and engaged in latching arrangement to maintain said contacts engaged, said bimetal extension operable in response to being heated to open out for releasing said spring arm structure.

4. A thermal responsive switch means for an electric heating device comprising a spring arm structure comprising a pair of spring arms, one of said arms carrying a contact, a bimetal element having another contact adapted for contacting engagement with contact on said spring arm and further provided with an extension constructed to latch with said other spring arm, said spring arm structure moved to first bring said contacts together and subsequently moving the spring arm, other than the one carrying the contact, relative to the element and the spring arm carrying said contact to latch same lvvith the extension, said bimetal element responsive to a predetermined rise in temperature to -Which same is sub ected to release said latch and disconnect said contacts.

ALFRED D. SLATKIN.

References Cited in the file of this patent UNITED STATES PATENTS Number 

